The understanding of light.

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Introduction

The understanding of light has developed mainly since the 1600's. In 1666, Isaac Newton discovered that white light is made up of all colours. Using a prism, he found that each colour in a beam of white light could be separated. Newton proposed the theory that light consists of tiny particles that travel in straight lines through space. He called these particles corpuscles, and his theory became known as the corpuscular theory. About the same time that Newton proposed his theory of light, the Dutch physicist and astronomer Christiaan Huygens suggested that light consists of waves. He proposed the wave theory to explain the behaviour of light. ...read more.

Middle

Maxwell's work gave the wave theory of light a solid foundation. Maxwell's electromagnetic theory also did away with an idea that had stood in the way of scientists' acceptance of the wave theory for more than a century. Scientists felt they had to find the medium through which light waves travel. They reasoned that if light travels as waves, there must be something for them to travel through. But for light, this something could not be matter, because light can travel in a vacuum. To get around this difficulty, scientists suggested that the medium light travelled through was the ether. All attempts to observe or measure the properties of the ether failed. ...read more.

Conclusion

The concept of light as quantized energy explained how light behaves as a particle in certain experiments, instead of as a wave. These particles of light came to be called photons. In 1913, the Danish physicist Niels Bohr proposed that the energy of atoms was also quantized. When energy is given to an atom, either by a collision or by shining light on it, the atom can accept only certain values of energy. In this way, the atom becomes excited. When it de-excites, it must get rid of the extra energy. One way it can do this is by emitting a photon that carries the energy away. Each type of atom accepts a different set of energies. Thus, when atoms emit light, the photons from one type of atom differ in energy from the photons from other types of atoms. ...read more.